Non-caking detergent material

ABSTRACT

A POWDERED DETERGENT COMPOSITION WHEREIN THE DETERGENT IS DERIVED FROM AN UNSATURATED ACID CONTAINING AT LEAST FOUR CARBOXYLIC GROUPS PER MOLECULE WHICH HAS BEEN ESTERIFIED WITH ONE OR MORE HYDROXY CONTAINING ORGANIC COMPOUNDS, E.G., ALCOHOLS, IS PRODUCED BY MIXING THE DETERGENT COMPOSITION WITH WATER TO FORM A PASTE WHEREIN AUTO-HEATING OF THE PASTE OCCURS THEREBY DRYING THE PRODUCT, THE DRIED PRODUCT IS THEREAFTER COMMINUTED TO FORM A POWDER.

United States Patent 3,598,744 NON-CAKING DETERGENT MATERIAL Fred Smeets, Tienen, Belgium, assignor to La Citrique Beige N.V., Tienen, Belgium No Drawing. Continuation-impart of application Ser. No. 563,816, July 8, 1966. This application July 5, 1968, Ser. No. 742,541

Claims priority, application United Kingdom, July 5, 1967, 31,010/67 Int. Cl. Clld 1/14, 3/065, 11/00 US. Cl. 252-99 1 Claim ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of Ser. No. 563,816, filed July 8, 1966.

This invention relates to the production of noncaking cleaning powders for scouring or laundering, and particularly relates to such powders which include as a surfactive material a sulphonate salt of an ester derived from unsaturated polycarboxylic acid material described in the above-mentioned, copending application Ser. No. 563,810; or the improved surfactive material described in patent specification No. 742,540 filed on the same date as the present application.

Powdered cleaning compositions contain several constituents, including detergent and/or other surfactive compounds, for instance one or more alkyl aryl sulphonates and/or alkyl sulphates or sulphonates, e.g. sulphates of fatty alcohols or sulphonates or alkyl benzenes, usually present in proportions of from 20 to 30% by weight based on the total composition, together with builders and/ or fillers, including for example polyphosphates, silicates, perborates, inorganic carbonates and sulphates, and other constituents well-known in the detergent-compounding art, including optical whiteners and antiredeposition agents.

It is necessary to produce the final cleaning composition in the form of a dry powder which is non-caking, and in order that the powder may be handled easily during laundering or other cleaning operations, it is necessary with conventional cleaning compositions to form a slurry thereof and to effect a spray-drying operation. Spray-drying however is a costly process, and involves large investment in equipment, and operation requires the evaporation of large quantities of water.

Patent specification No. 563,816 describes unsaturated acid material derived from the controlled pyrolysis of an alkaline earth metal salt of citric acid, namely by heating the said alkaline earth metal salt for a period of time, and at temperature preferably not less than 230 C., more preferably in the range of 250 C. to 400 C., and particularly in the range 300 C. to 375 C., until an increase in titratable alkalinity is obtained, until not more than 32% of the original citric acid salt remains and preferably until not more than by weight of the original citric acid salt remains, whereupon the product is hydrolyzed using conventional hydrolysis techniques for the production of acids from their corresponding salts, whereupon an unsaturated acid material is obtained.

The chemical identity of the said unsaturated acid material has not precisely been determined, although it is Patented Aug. 10, 1971 different from, although it may contain, aconitic acid, which may be removed from the material if desired either before or after the hydrolysis step, together if desired with any inorganic salt generated during the controlled pyrolysis. From analysis carried out on the pyrolysis product it appears that the unsaturated acid component is a derivative of an as yet unidentified unsaturated acid containing more than three carboxylic acid groups per molecule.

The said acid material (or its salt precursor) may be sulphonated by contacting a solution of the said material with bisulphite ions under acid conditions. Thus a bisulphite or sulphite compound may be introduced into the said material, or S0 injected into the said solution, to produce a corresponding sulpho-polycarboxylic acid material or salt thereof, the sulpho-salt thereafter being hydrolyzed. By these means a sulpho-polycarboxylic acid material is obtained.

Surfactive material comprising a sulphonate salt of an ester material may be obtained from the said unsaturated polycarboxylic acid material, or the corresponding sulphoacid material, by the esterification thereof with one or more alcohols, the resulting ester product being sulphonated if necessary to obtain the corresponding sulphonate ester. The sulphonate ester produced by either method is then neutralized to produce the corresponding sulphonate salt of ester material. The specific properties of this surfactant material are a function of the metal radical of the sulphonic acid salt, and also a function of the degree of esterification and the chain-length and distribution of the alcohol residues used in the esterification process.

One of the advantages of surfactive materials thus prepared is that they are biodegradable. Another advantage is that they possess the properties of both soaps (i.c. salts of fatty acids) and detergents (e.g. of sulphate or sulphonate of fatty alcohols), and possess advantages over both. Thus while displaying the cleansing power of soaps, they have a low sensitivity to water-hardness, and are equally efiective in alkaline and neutral media, and have a particularly low value for critical micelle concentration (C.M.C.). They have good suspending properties, including the prevention of precipitate of calcium or magnesium salts from hard water, and are effective in reducing the surface tension of aqueous media in very low concentrations of a few tenths of one part per million, while useful lowering of surface tensions to about 35 dynes per cm. is obtainable in concentrations of from 1 to 10 parts per million.

The sulphonate salt of ester material constituting the surfactive material may be adapted to a wide range of uses by the selection of the chain length(s) of the alcohol or mixture of alcohols used in the esterification step. Thus broadly one or more (l -C monohydric alcohols may be used. For detergents suitable for laundering wool or synthetic fibres, e.g. nylons or polyesters, at relatively low temperatures of from 20 to 65 C., one or more C C preferably one or more C -C monohydric alcohols may be used. A particularly useful sulphonate ester is one derived from a 0., together with a C alcohol. For detegents suitable for laundering cotton at relatively high temperatures of for example from 70 to 95 C., a mixture of from 35 to 15 mole percent of one or more C -C monohydric alcohols and from 65 to mole percent of one or more C -C monohydric alcohols may be used.

An improved surfactant material derived from the said unsaturated polycarboxylic acid material is decribed in patent specification No. 742,540, filed on the same date as this specification. The said improved surfactive material comprises the ester reaction product of at least one hydroxy equivalent of a non-ionic surfactant containing at least one hydroxy group, with not more than four carboxylic acid equivalents of an unsaturated polycarboxylic acid material or the corresponding sulpho-acid material, the ester thereby obtained being converted to the corresponding sulphonate salt; the said unsaturated polycarboxylic acid material being obtained by a process which comprises pyrolysing an alkaline citrate at a temperature of from 250 C. to 400 C. for a period of time until an increase in titratable alkalinity of the reaction mixture is obtained, and converting the unsaturated salt material thereby obtained to the corresponding acid material.

Non-ionic surface active agents containing one or more free hydroxyl groups which may be used to esterify the polycarboxylic sulphonic acid to produce the said improved surfactive material include those described in Chapter 8 of Surface Active Agents by Schwartz- Perry-Interscience Publishers Inc., New York, 1949. Specific classes of non-ionic surface-active agents include alkoxylated hydrophobic hydroxy compounds, e.g. the reaction product of an alcohol or phenol with more than one mole per hydroxy group of ethylene or propylene oxide. Suitable alcohols which may thus be alkoxylated include C -C aliphatic alcohols, for example, fatty alcohols, oleyl alcohols, glycols, alkylated fi-naphthol, oxo alcohols, ether alcohols, secondary alcohols made by reducing the ketones obtained by pyrolysis of synthetic paraflin wax fatty acids, polyalkyl cyclohexanols made by the reduction of the corresponding isophorones, sod oil, alkyl phenols, complex phenols derived from condensation of a simple phenol with an aldehyde or ketone e.g. condensation of alkyl cyclohexanone and phenol.

Preferred non-ionic surface-active agents which may be used to esterify the acid material according to the invention, are the polyethyoxylated or polypropoxylated C -C monohydric or polyhydric aliphatic or cyclic alcohols, e.g. oleyl, cetyl and stearyl alcohol, wax and tallow alcohols, and cyclic alcohols such as naphthols, phenols, alkyl phenols, e.g. C C alkyl phenols, and bisphenols.

Other alcohols which may be used include ether alcohols, e.g. the Carbitols (the term Carbitol is a trademark) and polyglycols, sugar alcohols and partial esters thereof e.g. sobitol esters, glycols including ethylene and propylene glycols, and pentaerythritol or partial esters thereof, and Cellosolve (a trademark).

Preferably the non-ionic surfactants employed as esterification agents according to the invention are those which contain a single free hydroxyl group.

The improved surfactive ester material may be an ester in which at least 25%, e.g. 25 to 75%, or all, of the carboxylic groups of the polycarboxylic acid material have been reacted with the non-ionic surfactant. The remaining carboxyl groups (if any) preferably being esterified (before, during or after the esterifieation with the said non-ionic surfactant), with one or more monohydric or polyhydric alcohols, e.g. -0 monohydric alcohols, (which may be straight or branched chain alcohols, including keto-, etherand sugar-alcohols). If desired some or all of the remaining carboxylic groups may be reacted so that their acid function becomes modified in other ways, for example by conversion to salts (e.g. sodium or ammonium salts), amides or amines.

The improved surfac-tive ester group so produced may be in the form of a simple ester, which may be a full, partial and/or mixed ester, or it may be in the form of a complex ester, in which at least two polycarboxylic acid residues are joined by a polyhydroxy alcohol residue, e.g. a glycol or glycerol residue. The formation of such a complex ester structure may be effected either before, during or after, reaction of the unsaturated polycarboxylic acid material (or the corresponding sulphoacid material) has been partially esterified with the non-ionic surfactant.

After the esterification reaction has been completed, sulphonation across the double bonds of the polycarboxyl- 1c acid residue may be effected, and the resulting sulphoester neutralized to form the corresponding sulphonate derivative (e.g. sodium sulphonate derivative). If a sulphopolycarboxylic acid material has been used for the esterification, the final ester may be neutralized to form the corresponding sulphonate salt.

In cleaning compositions containing such surfactant materials, the proportion of surfactant material necessary to achieve a given level of cleaning is much less than the proportion of hitherto-used conventional detergent components, and useful detergent compositions are obtained with from 2% to 25% by weight based on the total composition, of the sulphonate ester material, although greater or less proportions may be used if desired. The said sulphonate ester materials may be associated with one or more conventional detergent compounds, e.g. alkyl aryl sulphonates and/or alkyl sulphates or sulphonates.

It has now surprisingly been discovered that cleaning powder compositions containing sulphonate ester material derived from unsaturated salt material obtained as hereinbefore described, may be obtained as homogeneous noncaking powders by a simple process of forming an aqueous paste of the said detergent composition, and allowing the said paste to solidify by standing to produce a friable solid mass, and grinding or otherwise comminuting the solid mass to a powder.

Thus the process of the invention renders the use of spray-drying techniques unnecessary, and moreover the resultant powder besides being non-caking, is less waterrepellent, thus permitting faster cleaning or dissolution.

The amount of water added to the said detergent compositions should be the maximum possible to be completely absorbed in the detergent composition without residual water being present after absorption has taken'place. With such a proportion of water, and the initial mixture is a moist paste, which undergoes spontaneous heating on standing with the resulting formation of a friable solid.

The actual amount of water to produce a priable solid according to the invention depends on the proportions of the various constituents of the cleaning, e.g. detergent or scouring composition. Thus for a powder containing 40% of polyphosphates, the amount of water may be in the range of from 5% to 25%, preferably between 10% and 20% by weight, based on the total composition.

The proportion of weight of sulphonate ester that may be incorporated in the powder composition may generally be substantially higher than the detergent compound present in conventional detergent or scouring powders, before the onset of caking.

The following example of the invention is provided:

EXAMPLE Preparation of a heavy-duty detergent powder An aqueous surfactant solution of composition (A) and a blended mixture of composition (B) of builders were continuously mixed in order to obtain a homogeneous paste, in a ratio of (A)/(B) of 0.292, all parts being by weight.

5 parts of a detergent sulphonic acid salt of an ester material, prepared as hereinafter described.

2 parts of ethoxylated nonyl phenol 15 parts of water Trace amounts of optical whitening agent; Na carboxymethyl cellulose, and perfume.

35 parts of Na-tripolyphosphate 20 parts of Na-perborate 7 parts of Na-metasilicate 15 parts of Nat-sulphate The detergent sulphonic acid salt material was prepared as follows.

56.4 litres of an aqueous solution of sulphoacid material, having a concentration of 11,000 milliequivalents/ litre, obtained by the controlled pyrolysis of calcium citrate at a temperature of from 250' to 350 C. for three hours, followed by hydrolysis and sulphonation of the resulting acid material; 46.9 kgms. of ethoxylated nonylphenol, obtained by reacting 8.5 moles ethylene oxide per hydroxyl equivalent, and having a hydroxyl value of about 94.0; and 45 kgms. of n-butyl alcohol; were introduced into a reaction vessel provided with an agitator and the contents reaction with stirring at a temperature between 60 C. and 85 C. under a reduced pressure of about 100 mm. Hg. An azeotropic mixture consisting of butyl alcohol and water was distilled off and collected in a water separator, the supernatant alcoholic layer being returned continuously to the reaction vessel. After 8 hours the reaction was almost completed and the remaining acidity was neutralised to pH 7.0, with sodium hydroxide solution, and excess alcohol removed by distillation under reduced pressure.

When compositions (A) and (B) were blended, the final composition contained approximately 7% of total surfactant material, and was in the form of a moist paste. On standing, heat was spontaneously generated in the paste, which gradually dried out, and became friable after about 6 hours.

The powder was ground and sieved to obtain a free flowing powder of attractive appearance and good particle size distribution, with a bulk density of about 0.55 grms./litre.

What is claimed is:

1. A method of producing a powdered cleaning composition consisting essentially of a surfactive sulphonate ester material and one or more builders selected from the group consisting of polyphosphates, silicates, perborates, inorganic carbonates and sulfates, said sulfonate ester material being the sulfonate salt of an ester of a nonionic surface active agent containing one or more free hydroxyl groups with an unsaturated polycarboxylic acid material having more than 3 carboxylic acid groups which is obtained by a process which comprises pyrolyzing an alkaline earth citrate at a temperature from 250-400 C. for a period of time until an increase in titratable alkalinity of the reaction mixture is obtained and until not more than 32% by weight of the original citrate acid salt remains in the reaction mixture, and converting the unsaturated salt material thereby obtained to the corresponding acid material; said sulfonate salt being formed by sulfonation of the double bonds of the unsaturated polycarboxylic moiety either prior to or subsequent to the esterification reaction; said method of producing a powdered cleaning composition comprising: (1) formation of an aqueous paste of the constituents of said cleaning composition without residual water being present and (2)allowing said paste to solidify to produce powdery mass.

References Cited UNITED STATES PATENTS 2,448,831 9/1948 Roberts et a1. 260537 LEON D. ROSDOL, Primary Examiner D. L. ALBRECHT, Assistant Examiner US. Cl. X.R. 2s2 -13s, 161 

